The group of five galaxies known as Stephan\u2019s Quintet are also called the Hickson Compact Group 92 (HCG 92). “Quintet\u201d is a misnomer, as only four of the galaxies are truly close together. Credit: NASA\/ESA<\/p>\n<\/p>\n
The early universe was supposed to be a quiet neighborhood. Standard models describe small galaxies growing slowly and mostly alone, pulling in gas over billions of years.<\/p>\n
The James Webb Space Telescope<\/a> keeps finding exceptions, and the latest one is dramatic. At least five galaxies are piling into each other just 800 million years after the Big Bang, packed into a patch of space not much wider than the Milky Way.<\/p>\n Researchers at Texas A&M University<\/a> found the system in Webb\u2019s deep images of the GOODS-South region. They nicknamed it \u201cJWST\u2019s Quintet,\u201d a nod to Stephan\u2019s Quintet, the well-known group of interacting galaxies about 290 million light-years from Earth.<\/p>\n Five galaxies in a tight spot<\/p>\n The whole system fits inside a region roughly 80,000 light-years across. The five galaxies, labeled ELG1 through ELG5, share that space with more than 17 galaxy-sized clumps of stars.<\/p>\n Individual members sit tens of thousands of light-years apart. That sounds distant, but for galaxies it counts as close quarters, and gravity has already tangled them together.<\/p>\n Combined, the group holds about 10 billion Suns\u2019 worth of stars. It is also forming\u00a0new stars<\/a>\u00a0at roughly 250 solar masses per year, about 10 times the pace of typical galaxies of similar mass at that time.<\/p>\n The system turned up in data from the JWST Advanced Deep Extragalactic Survey<\/a>, one of the deepest imaging campaigns Webb has run.<\/p>\n The Hubble Space Telescope had photographed several of these galaxies years earlier. Only Webb could show that all five sit at the same redshift of 6.7, which places them together in space rather than scattered along our line of sight.<\/p>\n A merger this crowded \u201cwas not expected so early in the universe\u2019s history,\u201d said Dr. Weida Hu, a postdoctoral researcher at Texas A&M and the study\u2019s lead author. Astronomers thought early mergers usually involved two galaxies, sometimes three.<\/p>\n Oxygen where it should not be<\/p>\n The oddest evidence lies entirely outside the galaxies. Webb picked up a large halo of glowing gas that surrounds and connects four of the five members.<\/p>\n The glow comes from ionized oxygen and hydrogen. Oxygen forms inside stars, so its presence in the space between galaxies means something hauled it out of them.<\/p>\n The team\u2019s analysis points to gravity. Tidal forces during the pile-up stripped enriched gas away from the galaxies, rather than winds from exploding stars pushing most of it out.<\/p>\n Before Webb launched, astronomers expected that kind of widespread enrichment to appear more than a billion years after the Big Bang. This system had already achieved that level of enrichment by 800 million years after the Big Bang.<\/p>\n Echoes of Stephan\u2019s Quintet<\/p>\n Astronomers can watch similar chaos much closer to home. In Stephan\u2019s Quintet<\/a>, five galaxies crowd one small patch of sky, and past collisions there have littered the group with debris.<\/p>\n One member, NGC 7318b, is currently smashing through that debris at over two million mph (3.2 million km\/h). Its passage drives a giant shockwave, which researchers recently mapped with the WEAVE spectrograph on the William Herschel Telescope.<\/p>\n The parallel runs deeper than a borrowed name. Both systems show bridges of gas and stars pulled between neighbors, a classic fingerprint of tidal interaction.<\/p>\n The main difference is time. Light from Stephan\u2019s Quintet left about 290 million years ago, while light from JWST\u2019s Quintet has traveled for almost 13 billion years, since the universe was about six percent of its current age.<\/p>\n A recipe for dead galaxies<\/p>\n The discovery may also help with a separate Webb puzzle. The telescope keeps finding massive galaxies that had already shut down star formation while the universe was still young.<\/p>\n Galaxies that big and dead should not exist so early. They needed to build enormous stellar mass and then burn through their gas in a hurry, and quiet, steady growth cannot do both.<\/p>\n A multi-galaxy pile-up can. Violent galaxy collisions<\/a> compress gas, trigger runaway star formation, and then strip and scatter the leftover fuel.<\/p>\n The quintet\u2019s mass and star formation rate line up with the histories inferred for those early dead galaxies. Hu and his colleagues argue the system could be a direct ancestor of that population.<\/p>\n Theories of how galaxies come together \u201cneed to be updated to match reality,\u201d said Dr. Casey Papovich, a professor of physics and astronomy at Texas A&M and co-author of the study.<\/p>\n What comes next<\/p>\n Follow-up observations will track how gas and galaxies move inside the system. Those measurements should show whether the five members are truly headed for a single, giant merger remnant.<\/p>\n One system is still just one system. Whether crowded early mergers like this are common, or whether this survey simply got lucky, will take more deep fields to answer.<\/p>\n The study was published in the journal Nature Astronomy<\/a>.<\/p>\n How to get involved<\/p>\n Classify real telescope images of colliding and merging galaxies with Galaxy Zoo<\/a>, the long-running Zooniverse project whose volunteer classifications have appeared in dozens of published studies.<\/p>\n Browse the NASA citizen science<\/a> portal for active projects built on real mission data, many of which need nothing beyond a laptop and some patience.<\/p>\n Join The Planetary Society<\/a> to support advocacy for continued funding of space science missions like Webb.<\/p>\n Support DarkSky International<\/a>, which works to cut light pollution so backyard observers can still find targets like Stephan\u2019s Quintet.<\/p>\n Connect with Astronomers Without Borders<\/a> to find observing programs and events that bring amateur stargazers from across countries together.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"The group of five galaxies known as Stephan\u2019s Quintet are also called the Hickson Compact Group 92 (HCG…\n","protected":false},"author":2,"featured_media":1178034,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[3844],"tags":[70,413,16,15],"class_list":["post-1178033","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-science","tag-space","tag-uk","tag-united-kingdom"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@uk\/117187034756695387","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/1178033","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/comments?post=1178033"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/1178033\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media\/1178034"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media?parent=1178033"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/categories?post=1178033"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/tags?post=1178033"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}